The problem is IE cannot assert Barry lied to Grusing - Barry has to give that testimony himself. At this point in time we have Barry confirming the location data was accurate in terms of the below conversation.
The State case is that BM was moving around the house - and he was asked if he was looking for SM. Barry confirms that he was chasing a chipmunk. So sure, IE could try to introduce expert evidence that drift exists as a phenomenon but there is no way to prove that it actually was drift at that moment. And given Barry said the data was accurate it seems this will be simple to prove.
In particular I suspect a Court would not give IE much rope in terms of suggesting BM was tricked into lying, if BM himself does not testify to it. IE does not know if BM was tricked or not and what he tells her out of court is not admissible of course.
Grusing told Barry that when he arrived that afternoon, his phone went around the house “quite a bit.” Barry was nodding his head and saying, “Mhhmhh, mhhmhh.” SA Grusing asked, “Were you looking for her?” Barry said, “I shoo--, | shoot chipmunks.” SA Grusing asked, “You shoot chipmunnks?” said, “I shoo--, | shoot chipmunks.” SA Grusing asked, “You shoot chipmunnks?” Barry said, “Yeah.” SA Grusing said it looks like he was chasing one. Barry said, “Yeah, I was, I’ve shot 85 chipmunks because they got into my furnace and cost me a bunch of money. said, “Yeah, I was, I’ve shot 85 chipmunks because they got into my furnace and cost me a bunch of money. So, when [’m home...” SA Grusing interrupted and asked if he used a .22, and Barry replied, “Twenty-two. So, when I’m home I just walk around and shoot ‘em. Just keep going around the house.” (Barry made circular motions with his right arm.) He said, “Everytime I go around the house, I’ll see another and I'll shoot it.” SA Grusing told Barry that activity would explain his phone’s behavior, adding that he left his driver door open in the garage before he went to the first patio. Barry said, “Mhhmhh,” and said, “Yeah, shootin’,” while nodding his head during the description of movement. He added, “No, I’m shootin’chipmunks. I’ve done that ever since we’ve moved in.” added, “No, I’m shootin’ chipmunks. I’ve done that ever since we’ve moved in.” SA Grusing asked Barry if he remembered doing it that day. He nodded his head and said, “Mhhmhh, oh yeah.”